An underwater robot that’s the brainchild of a 12-year-old girl from Massachusetts could be deployed someday in the war against marine plastic pollution.

One of the 30 finalists in the Broadcom MASTERS competition (which stands for mathematics, applied science, technology and engineering as rising stars) is Anna Du, a student from Massachusetts.

Image: Broadcom Masters

Her project is called ‘Developing a Smart Infrared Based ROV to Identify Microplastics in Marine Environments’ – ROV stands for remotely operated vehicle. Inspired by a visit to the beach, where she was struck by the volume of plastic littering the sand, Du has developed an underwater vehicle fitted with an infrared camera that can detect plastic resting on the seabed.

The problem of plastic pollution in the ocean is widely acknowledged and well documented. Yet solutions are still only starting to take shape.

Image: World Economic Forum

Each year, around eight million tonnes of plastic ends up in the sea, and by 2050 the amount of plastic pollution in the world’s oceans will outweigh all the fish living there.

The remains of a sperm whale found in Indonesia in mid-November demonstrate the extent of the plastic pollution problem. Almost 6 kg of plastic waste was found in the animal’s stomach, including 115 cups. Plastic has even been found inside freshwater fish living in the Amazon basin. Fish ranging in size from 4cm to almost 30cm, including the parrot pacu, the redhook silver dollar, and the red-bellied piranha, were all found to have consumed plastics and polymers.

Du decided to take part in the competition after seeing the extent of plastic litter at the beach, and how varied it was. “As I was collecting it, I couldn’t help but notice just how much plastics there were,” she says.

Different types of plastic absorb and reflect light in their own unique way, depending on their composition. This is the basis of many automated plastic recycling facilities – light is shone onto the flow of plastic along a conveyor, sensors detect which light is reflected and can group the plastic waste according to type.

The use of light to detect substance composition informed the choices Du made when developing her ROV. Its camera takes photos of the surface of the seabed and compares those images with a reference library she developed based on an online database. That allows it to tell plastics apart from other types of materials.

“The real invention here is the sensing,” roboticist and engineer Dana Yoerger told the Smithsonian Institute.